Hydro Energy

Hydroelectricity produced from dams is easily the most popular source of renewable energy used today. There are more uses for hydropower than just dams though. Even hundreds of years ago tidal mills were being used. Modern uses of hydropower make use of waves, tides, rivers, and every other source of flowing water.

Types of Hydro Power

There are four primary types of hydro power or hydroelectricity; wave, tidal, ocean thermal, and dams. Technically all of these sources of energy from water are actually driven by the Sun and other forces. Waves are caused by the winds which are created by temperature differences in the atmosphere due to the uneven heating of Earth by the Sun. Tides are created by the gravitational pull on our oceans by the Sun and Moon. Ocean thermal energy relies on temperature differences between surface and deep ocean water caused by heating from the Sun. Dams rely on the evaporation and condensation cycle which is powered by the Sun. Essentially hydro power is the harnessing of energy in moving water regardless of why or how that water is moving.

Uses of Hydro Power

Elephant water clock from Al-Jazari's manuscript. Image by Al-Jazari.

One of the earliest uses of hydro power is in irrigation for agriculture. Agriculture is among the first technological advances made by mankind and irrigation followed soon after. Since those times hydro power has been used for telling time (water clocks), creating compressed air to power machinery, as working fluid in compressed hydro power networks, and in water wheel mills. Modern use of hydro power has expanded on the water mill by connecting to a generator for generating electricity. As mentioned above tides, waves, and temperature differences are also all harnessed for generating electricity through various technological means. Recreation is also a use of hydro power in the form of surfing, rafting, and other activities.

Environmental Impact of Hydroelectricity

All forms of hydroelectricity have zero carbon dioxide and other pollution emissions except during the manufacturing of materials like concrete, steel, and other components that go into the technology used. This makes hydroelectricity a viable alternative energy source to combat global warming caused by greenhouse gas emissions.

One major concern with hydroelectricity is damage and alteration of the environment where hydro power technology is placed. This is a particularly large issue with dams that require large reservoirs to be created upstream submerging hundreds or thousands of acres below water and drastically changing the ecosystem. Additionally dams can cause problems for fish and other aquatic life. Turbines can kill fish and other animals. Migration patterns are often interfered with resulting in lower fish counts year after year. This is particularly a problem when it comes to salmon and other fish that swim upstream to spawn. Alteration of the ecosystem by creating reservoirs can also lead to algae blooms and other microbial problems that can result in permanent water quality problems for humans and other life.

Tellico Dam was delayed for more than two years over legal trouble caused by concerns over the impact to an endangered species, the Snail Darter, shown here.

Tidal barrages cause similar problems to dams. Even tidal stream generators, wave generators, and other hydro power technology can damage sensitive marine ecosystems if care isn’t taken when placing and maintaining these systems. Overall environmental impact is minimal as long as proper planning and execution is taken with dams and barrages being the major exception.